Company's standard cost for raw materials is per pound and it is expected that each metal shelf uses pounds of material. During October Year 2, pounds of materials are purchased from a new supplier for and shelves are produced using pounds of materials. Which statement is a possible explanation concerning the direct materials variances? A. The purchasing manager paid more than expected for materials. B. The overall materials variance is positive; no further analysis is necessary. C. Production workers were more efficient than anticipated. D. The production department had to use more materials since the quality of the materials was inferior.